Steam safety-valve.



No. 793,947. PATENTED JULY 4, 1905. J. H. MILLETT & F. A. HANNAH.

STEAM SAFETY VALVE.

APPLIOA'IION FILED JUNE 29,1904.

Izwadunsz. (-75% /1- Mm UNITED STATES Itatented July 1, 1905..

PATENT OFFICE.

JOSHUA U. hll LLE'lT, O1 MALDEN, AND FREDERICK AUGUSTUS lflANNAl-l, OF MEDFORD, MASSACHUSETTS, ASSTGNORS TO CROSBY STEAM GAGE AND VALVE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

S'l'EAWl EAFET'Y VALVE.

SPECIFICATION forming part of Letters Patent NO. 793,943, dated July 4;, 1995.

Application filed June 29, 1904:- Serial No. 214,632.

To m/Z'Z 7117mm if; mar/y concern:

Be it known that we, JOSHUA H. NlILLF/WP, a resident of Maiden, and FREDERICK AUeUs'rUs HANNAH, a resident of Med ford, in the county 5 of Middlesex and State of Massachusetts, citi- Zens of the United States, have invented certain new and useful Improvements in Steam Safety-Valves, of which the :lollowing is a specification.

i Our invention relates to steam safety-valves; and its object is to provide a valve that will operate with the least possible iriction.

The invention is illustrated by the accompan yi n g d rawings, in which I Figure 1 is a vertical central section of a valve embodying our improvement. Fig. 2 is a plan view on the line 2 2, Fig. 1.

Similar numbers rel-er to similar parts in the two drawings.

1 is a valve furnished with the base 2, in which is located the pop-chamber 3, with its outlets A controlled by the ring 5 in threaded engagement with the valve-casing 6 and locked in place by the bolt 7. In the base 2 are lo- 2 5 cated also the annular valve-seats 8 and 9, on

.which is seated the valve proper, which we call the disk 10. This disk 10 is located in the cage or guideway 11, which is attached to the base 2. The top of the cage 11 forms the bottom of the spring-chamber 12, mounted on the Valve-casing 6. Through the top of the cage 11 extends the pintle 13 of the sriiring-washcr 14, the end of which pintle engages loosely the center of the disk 10. The

springloismountedin the spring-chamber12.

Disks now employed in steam safety-valves have one or more arms, wings, or projections which are in sliding contact with some part of the valve structure and serve to guide the disk as it travels from and to its seat. Any inequalities in the pressure of the spring upon the disk cause these guiding-arms oi the disk to tilt and bind, thus greatly impairing the effective action of the valve. This tilting and binding arise also whenever the sliding contact of the guides is in any way disturbed. if these arms or guides are located below the disk, as is usually the case,they are constantly enveloped in steam, and the steam by its corrosive action causes them to stick, and it also abrades or furrows the valve-seat as it flows out along the line oi. these guides. W'e overcome these difliculties by employing a disk with spherical sides and without any arms, wings, or projections to serve as guides, and we locate this disk in a cage or guideway, in which it slides freely and whose vertical bars or walls serve to guide it. This cage or guideway may be made to contact with and guide the disk along such vertical lines as may be desired, or it may be a cylinder. The drawings show such a disk, which constitutes the central zone of a sphere and may be defined as the middle frustum of a sphere, for that is precisely what it is, located in a cage having 6 5 four vertical guide-bars 16, each oi which contacts with the disk at approximately a single point 17 and continues so to contact at only a single point however much the disk may rotate. The frustum of a sphere is any part 7c comprised between two parallel sections, and the middle lrustum of a sphere is that whose ends are equal circles. We extend the use of the term middle irustum to include a frustum composed of the adioining parts of the two hemispheres, though these parts are not absolutely similar. Substantially all friction between the disk and its guiding-cage is in this way overcome or prevented. The cage 11 serves to imprison the disk and helps to pre- 0 vent its escape in case of accident to the valve. it is obvious that the diameter of the sphere, of which the disk constitutes the central zone or middle frustum, must be just less than the inner diameter of the cage, and it is equally 35 obvious that the disk must be thick enough. or the cage shallow enough to always preserve the contact described by limiting the movements of the disk. in actual operation in a valve properly constructed a disk oi the 9 relative size shown in the drawings will never rotate enough to force it against the llange at the top ol the guiding-cylinder.

Another feature Oili our invention is the 2. In a safety-valve the combination, with the valve-casing and spring, of a disk constituting the middle frustnm of a sphere and a guideway therefor arranged Within said casing, said disk being held to its seat by said spring; substantially as described.

In testimony whereof we have afiixed our signatures in presence of two Witnesses.

JOSHUA H. MILLETT. FREDERICK AUGUSTUS HANNAH.

\Vitnesses:

MARY T. HANLON, RALPH W. FOSTER. 

